Low Amniotic Fluid ( Oligohydramnios ) – What to expect?

In This Article

What is amniotic fluid?

Amniotic fluid is a warm, thin, pale yellow fluid that surrounds the fetus. It is highly significant for the fetus’s safe development and adequate growth during pregnancy. It is a blend of hormones, immune system cells, nutrients, and secretions from the fetus. An optimum amount of fluid should be present in the amniotic sac. Too low or too high quantities of amniotic fluid are considered adverse for the baby’s growth and development.

What’s its significance in fetal well-being?

Amniotic fluid is important in maintaining optimum conditions for the development and survival of the fetus in the womb. This fluid fills the amniotic sac as early as 12 days after conception.

Amniotic fluid cushions the baby and allows free floating of the umbilical cord.
Prevents the baby’s body from compressing the umbilical cord against the uterine wall.
Amniotic fluid quantity signals how well the fetal urinary system is working since the fetus excretes urine directly into the fluid.
It helps in lung development, maturation of the digestive system, and the sufficient growth of muscles and bones in the fetus.
Amniotic fluid covering maintains a stable fetal temperature stable.
It protects against infection.
This protective covering also keeps the baby safe from influences outside the womb.

How is the amniotic fluid index measured?

The amniotic Fluid Index (AFI) is a standardized indicator to assess the amount of amniotic fluid in a pregnant woman’s womb.

The ultrasound scans determine the level of Fluid in the amniotic sac.
The quantity of fluid varies with gestational age and from woman to woman. At 20 weeks 350 ml of fluid (approx) is standard. Around 25 weeks it is 670 ml of fluid, t at 32 – 36 weeks 800 – 1000 ml, and at 40 weeks, 550- 600 ml is considered normal.
Other two methods to estimate the fluid levels are AFI (Amniotic fluid index) calculation and MVP (Maximum vertical point) calculation techniques. An average reading as per AFI should be 8- 24 cm. Less than 8 cm of AFI is considered low. The average reading as per MVP should be 2 – 8 cm. Less than 2 cm of MVP is considered low.

What is oligohydramnios?

Oligohydramnios

Oligohydramnios is a condition where the amniotic fluid is less than expected for the baby’s gestational age.

This low fluid condition is diagnosed by ultrasound scans, probably around 18 – 20 weeks of gestation.
Oligo means little, and hydra means water. Amnios is the membrane around the fetus or amniotic sac
Amniotic fluid in the womb increases as pregnancy progresses until around 34- 36 weeks. After that, it starts to decline as pregnancy reaches its full term. However, an ultrasound scan reading with AFI less than 8 cm and MVP less than 2 cm is considered a low amniotic fluid condition.

What are the common symptoms of oligohydramnios?

Oligohydramnios present little or no symptoms in many women. However, the cues on fluid level inadequacy are picked up by the scheduled prenatal ultrasound scan readings.

The uterus measures smaller than anticipated for the baby’s gestational age.
Poor maternal weight gain.
Abnormal fetal heart rate
Reduced fetal activity and growth.
Frequent fluid leakage from the vagina.

Be aware of the type of vaginal leakage. Vaginal fluid flow could be the leaking of amniotic fluid, urine, or an increased vaginal discharge. Usually, amniotic fluid leakage is a large gush of clear, warm watery fluid from the vagina without any odor, with small tinges of blood. Whereas, an increased vaginal discharge is normally a thick white or yellow sticky-smelling fluid. If not sure, refrain from self-diagnosis. Seek medical intervention.

What are the causes of oligohydramnios?

The main causes of oligohydramnios can be both fetal and maternal.

Maternal factors

Dehydration in the mother.
Placental abnormalities, where the membranes rupture much earlier before the onset of the actual labor
Health conditions of mothers like preeclampsia, diabetes, obesity, and high blood pressure.

Fetal factors

Urinary tract or kidney-related birth defects in the baby
Post-term baby that is above 40 weeks of gestational age.
Chromosomal abnormalities.

How does it affect a healthy pregnancy?

Potential Risk associated with oligohydramnios depends on the gestational age of the pregnancy. A low amniotic condition when diagnosed early in pregnancy will have more ill effects.

When diagnosed as early as the second trimester, there is a risk of developing birth defects, miscarriage, or even stillbirth of the fetus.
Oligohydramnios can lead to labor complications as there isn’t enough fluid for the mobility of the fetus which in turn could lead to constriction of the umbilical cord during birth.
The risk of preterm labor is much higher.
Lack of sufficient amniotic fluid causes labor contraction to be more painful, breathing difficulties, and distress in the baby at the time of birth.
Higher chances of intrauterine growth restrictions in the fetus.
Improper lung development called pulmonary hypoplasia is another ill effect on the fetus.
Due to less fluid to move around, the fetus will have restricted mobility that may develop tightness in the joints which affects the development of bones and muscles.

How to handle a low amniotic fluid condition?

Ultrasound scan to diagnose oligohydramnios

Oligohydramnios need no medical treatment when diagnosed at the end of a full-term pregnancy.

More prenatal check-ups and close monitoring of the amniotic fluid levels will be sufficient to have a safe childbirth.
Eating healthy, hydrated, and adequate rest is very important.
Always watch out for any signs of infection like foul-smelling vaginal discharge, pain, or discomfort in the pelvic area.
Keeping a check on comorbidities like hypertension, and diabetes is necessary.
A planned C Section becomes mandatory along with amnioinfusion. It is a transfusion of saline water into the uterine cavity using a catheter placed in the cervix to replace the low levels of amniotic fluid.
Check with the gynecologist to know about additional screening procedures like high-resolution fetal ultrasonography, fetal echocardiogram, and a doppler ultrasound to diagnose the fetal heartbeat, and kidney functions and to evaluate the placental functioning.

References

https://www.babycentre.co.uk/a568740/low-amniotic-fluid-oligohydramnios
https://medlineplus.gov/ency/article/002220.htm
https://my.clevelandclinic.org/health/diseases/22179-oligohydramnios